US 3003359 A
Description (OCR text may contain errors)
Oct. 10, 1961 F. MAAsDAM POWER UNIT Filed June 25, 1960 2 Sheets-Sheet 1 INVENTOR. F' e 4 FELBER MAASDAM A TTORNE Y Oct. 10, 1961 F. MAAsDAM 3,003,359
POWER UNIT Filed June .25, 1960 l 2 Sheets-Sheet 2 INVENTOR. FELBER MAASDAM A TTORNE Y wal/Mu United States Patent 3,003,359 Patented oct.' to, 1961 Claims. (Cl. 74-142) This invention relates to improvements in power units or pulling devices of the type in which rotary motion is imparted to a cable winding drum through pawl and ratchet mechanisms, the latter being operated by an oscillatory lever.
More particularly, the invention relates to a reversible hand operated pulling unit having simplified `and improved means for controlling the retrograde movement of the winding drum when the latter is under load.
A primary object of the invention is to provide a power unit of the above-mentioned character having novel and simplied cam and spring means associated with the feed or lever pawl for rendering the same active and inactive with respect to the ratchet teeth of the winding drum, said means enabling the lever pawl to coact with the holding pawl for the winding drum in a simplified and more eicient manner.
Other objects and advantages of the invention will be apparent during the course of the following description.
In the accompanying drawings forming a part of this application and in which like numerals are employed to designnate like parts throughout the same:
FIGURE 1 is a perspective view o f the power unit according to the invention in its entirety,
FIGURE 2 is an enlarged fragmentary side elevation of the power unit in one operative position,
FIGURE 3 is a plan view of the unit shown in FIG- URE 2,
FIGURE 4 is an enlarged fragmentary side elevation of a feed pawl control lever and associated elements,v
FIGURE 5 is a fragmentary perspective view of the feed pawl and control means therefor and associated elements, v
FIGURE 6 is a fragmentary vertical section through one portion of the operating lever and showing the control cam and lever for the feed pawl,
FIGURES 7, 8 and 9 are fragmentary side elevational views illustrating the coaction between the feed and holding pawls for the cable winding drum during retrograde movement of the latter and further illustrating the novel means for rendering the feed pawl active and inactive.
The general construction of the power unit is disclosed in prior United States Patents 2,506,029 and 2,669,426, among others, and the general construction needs only to be described briefly herein.
With reference to the drawings, wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral 10 designates generally a rigid frame or yoke including spaced parallel arms 11 and 0pposite end portions 12, having heads 13 rigid therewith. Bifurcated connector elements 14 are swiveled to the heads 13 and carry anchor hooks 15, pivoted thereto at 16.
An operating handle or lever 17 is provided, including spaced arm extensions 18, engaging inwardly of the frame sides 11 and pivoted thereto at the longitudinal centers thereof by means of a transverse bolt 19, rigid with the frame 10.
A cable winding drum 20 for pulling cable 21, having hook 22, is journaled for rotation upon the bolt 19, between arm extensions 18. 'I'l1e drum 20 is provided `at one end with the usual ratchet teeth 23 for coaction with the feed and holding pawls to be described. A guide element 24 for cable 21 is fixedly secured to the frame 10,
as shown, and an anti-backlash guard 25 for the cable wound upon the drum 20 is also provided in surrounding relation to one side portion of the drum.
v The construction thus far described is largely conventional, and shown in the mentioned prior patents, and a more detailed description of the general construction of the power unit is therefore believed to be unnecessary herein.
A driving or feed pawl 26 for the drum 20 is pivotally mounted at 27 between the arm extensions 18 of operating lever 17, and the feed pawl 26 is vformed integral with a transverse sleeve 28, which receives the pivot element 27 rotatably. A pawl operating extension 29, formed integral with the sleeve 28, extends adjacent to one side of the operating lever 17, intermediate the ends of the operating lever. Ihe feed pawl 26 is .positioned for coaction with the ratchet teeth 23, as shown.
A holding pawl 30 for the winding drum 20 includes a transverse sleeve portion 31, rotatably mounted upon a transverse pin 32, extending between and rigid with the frame portions 11, near corresponding ends of the same. Ihe holding pawl 30 is positioned for coaction with the ratchet teeth 23, as shown. The holding pawl 30 is `biased toward engagement with the ratchet teeth 23 by a torsional coil spring 33, surrounding the sleeve portion 31 and having one end anchored to the frame 10 at 34, and itsV other end attached to an operating extension 35 yof the holding pawl at 36. YA spring loaded holding pawl lifting element or plunger 37 is bodily mounted upon the holding pawl 30 for coaction with the feed pawl 26 in a manner to be described, during retrograde movement of the winding drum 20 in a step-by-step manner Means forming an important feature of the invention are provided Vfor rendering the feed pawl 26 active and inactive with respect to the ratchet teeth 23 and to facili- .tate the coaction between the feed and holding pawls yduring the step-by-step retrograde movement 'of the winding drum. This means comprises a substantially cylindrical cup-like cam 38, mounted for rotation upon one converging portion 39 of one arm extension 18l of the operating lever 17. The cam 38 is rigid with a stud element 40, rotatable within an opening 41 of arm portion 39, and an operating level 42 for the cam 38 is rigidly secured to the lrotatable. stud 40 for rotation therewith and with the cam 38.
A coil spring 43 has a forward longitudinal extension 44 anchored at 45 to a lug 46 carried by the feed pawl operating extension 29. A rear longitudinal extension 47 carried by the spring 43 engages through an opening 48 in the forward portion of the peripheral wall 49 of cam 38. The spring extension 47 extends rearwardly across the cup-like cam 38, generally diametrically,-and has its rear terminal portion 50 slidably engaging an approximately .semi-circular curved peripheral cam portion or wall 51, as shown.
The edge 52 of the circumferential cam portion Slis curved soV as to slope gradually in opposite directions from a central high portion 5'3, toward low end portions 54, terminating at positive stops 55, formed upon the forward peripheral wall portion of the cam. Thus, when the cam 38 is turned by the operating lever 42 upon the axis of the stud 40, the spring extension 50 is adapted to ride over the curved or sloping camedge 52 from one low cam portion 54 to the opposite low cam portion S14, in either of which positions the spring extension engages one of the stops 55. Intermediate the low portions 54 of the cam, the spring extension 50 passes over thehigh portion 53 of the cam edge 52. As thisvaction takes place, the spring 43 attached to the feed paw1j26la`t v45 is shifted from one side to another beyond dead center,
vand the spring 43 is tensionedto shift vthefeed pawl 26 5 ing said spring extension and a sloping cam part including high and low cam faces slidably engaging said spring extension and stops adjacent said low cam faces engagable with said spring extension, and a lever secured to Said cam to turn the latter in opposite directions, whereby said spring attached to the feeding pawl is shiftable upon opposite sides of dead center with respect to the feeding pawl to render the feeding pawl active or inactive with respect to said ratchet teeth.
3. In a power device of the character described according to claim 2, wherein said cam is substantially cylindrical and cup-like and includes an annular peripheral Wall, said opening for said spring extension being formed through the forward portion of said peripheral wall and said cam part including the high and low cam faces extending circumferentially around approximately one-half the circumference of said peripheral wall at the rear side of the same and said stops are disposed in diametn'cally opposed relation on said peripheral wall.
4. In a power unit of the character described, as a 20 sub-combination, a rotary cable winding drum having spaced ratchet teeth on its periphery, an actuating lever for said drum, a feeding pawl pivoted to said lever and engagable with said ratchet teeth to turn said drum when the actuating lever is moved in one direction, a cam 25 rotatably mounted upon said lever near the feeding pawl and including an actuating part, said cam being cup-like and having an annular peripheral wall including a sloping edge cam portion extending circumferentially of the cam for substantially 180 degrees, said sloping edge cam 30 coil spring having one end attached to said feeding pawl 85 l2,890,857
6 and having an opposite end extension engaging through said side opening and bearing slidably against said sloping edge cam portion and engagable with said stops when the cam is turned in opposite directions for rendering the feeding pawl active or inactive.
5. In combination, a ifeeding pawl actuating lever, a feeding pawl pivotally mounted upon said lever and adapted for engagement with ratchet teeth of a drum or the like to be turned, a cup-like cam rotatably mounted upon said lever, an operating lever secured to said cam for turning the same in opposite directions, said cam having an annular peripheral wall provided with a side opening and including a sloping edge portion having a central high part substantially opposite said opening and end low parts terminating in stops, said stops being formed on said annular wall and spaced equidistantly circumferentially of the side opening, a coil spring attached to said pawl and having an end extension engagable through the side opening and extending across the cam substantially diametrically and slidably bearing upon said sloping edge portion and adapted to contact said stops when the cam is turned in opposite directions to render said pawl active or inactive, the cam shifting the spring beyond opposite sides of dead center with respect to the pawl and its pivot to render the pawl active and inactive.
References Cited in the iile of this patent UNITED STATES PATENTS 1,236,616 Snow Aug. 14, 1917 2,738,954 Du Bois Mar. 20, 1956 2,816,733 Du Bois Dec. 17, 1957 2,854,852 Clark Oct. 7, 1958 Homan June 16, 1959